CN114128310A - Projecting cancellation sound using a microphone - Google Patents

Abstract

The present invention provides audio systems, methods, and computer readable media having program code to receive harmonic signals related to rotating equipment, such as a vehicle driveline in some examples, and provide harmonic cancellation (or enhancement) signals. The harmonic cancellation signal is converted to an acoustic signal and a feedback sensor (such as a microphone) detects an error signal representative of acoustic energy at a first location in the environment. The projection filter filters the error signal to provide an estimated error signal at a second location in the environment, such as at the location of the occupant's ear. The adaptation module adjusts the cancellation signal based on the estimated error signal.

Description

Projecting cancellation sound using a microphone

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional patent application serial No. 62/848,888 entitled "SOUND bearing use microprocessing program" filed on 2019, 5, 16, which is incorporated herein in its entirety for all purposes.

Background

The present disclosure relates generally to systems and methods for minimizing an error signal indicative of an undesired sound at a location remote from a feedback sensor.

Disclosure of Invention

All examples and features mentioned below can be combined in any technically possible manner.

Various aspects include cancellation systems, methods, and/or program code for canceling or reducing undesired sound, particularly related to harmonics of rotating equipment, such as engine or other drive train harmonics, and/or other equipment, such as air conditioning equipment, fans, motor drives, and the like. The system, method or program code includes (or implements) a cancellation filter configured to generate a cancellation signal. The cancellation signal may be based on a reference signal received from a sensor, such as a tachometer or other sensor indicative of a number of revolutions, such as engine or drive train rotation (e.g., revolutions per minute), that provides a signal indicative of harmonics. The transducer is disposed at a first location within a sound environment (such as a vehicle cabin) and is configured to receive a cancellation signal and convert the cancellation signal into a cancellation audio signal within the environment. A feedback sensor, such as a microphone, may be disposed at a second location within the environment to output a feedback signal, which may be considered an error signal, that is representative of sound at the second location. The one or more projection filters may be configured to filter the feedback signal and/or the cancellation signal to provide an estimated error signal representing an estimated value of the undesired harmonic sounds at a third location remote from the first location and the second location. The adjustment module may be configured to adjust the cancellation filter based on the estimated error signal such that the cancellation audio signal destructively interferes with the undesired sound at the third location.

According to various examples, the sensor may indicate a rate of rotation of the engine and may provide engine harmonic information. In some examples, the sensors may provide rotational information about other parts of the drive train, such as the gearbox, transaxle, wheels, etc. In certain examples, the sensor may provide rotational information about other rotating equipment, such as a drive motor, e.g. for actuating a window, a wiper, etc., air conditioning equipment, a fan, etc. In some cases, the sensor may further provide one or more substantially sinusoidal signals indicative of one or more harmonics of the rotating equipment.

In a particular example, the feedback sensor may be a microphone to detect acoustic energy within an environment (such as a cabin of a vehicle), and the location of the microphone may be a roof, pillar, roof, or other location. In various examples, the third position is an expected position of an ear of the occupant. Thus, the feedback sensor signal may be a remote microphone signal and the estimation error signal may represent an estimate of the acoustic energy at the ear of the occupant. Thus, the estimated error signal may represent a virtual microphone located at a third location, e.g., where the roof microphone is "projected" to the occupant's ear.

In various examples, the estimated error signal is based on an estimated value of the acoustic relationship between the second location (microphone) and the third location (ear of the occupant). In a particular example, the estimated error signal may also be based on an estimated value of the acoustic relationship between the first location (transducer) and the third location (ear of the occupant), and an estimated value of the acoustic relationship between the first location (transducer) and the second location (microphone).

In a particular example, the one or more projection filters include a first filter configured to estimate a relationship between the second location and the third location, the first filter configured to receive and filter a feedback signal (the undesired sound at the second location) and output a first filtered signal, the first filtered signal being an estimate of the undesired sound at the third location. The first filter may be referred to as a projection filter, for example, because it "projects" the feedback sensor (microphone) to an alternative location (the occupant's ear) to produce an estimate of the feedback signal when the feedback sensor is located at the alternative location.

In some examples, the one or more projection filters further include a second filter configured to estimate a relationship between the first location (the transducer) and a third location (the occupant's ear), the second filter configured to receive and filter the cancellation signal and output a second filtered signal that is an estimate of the cancellation audio signal at the third location, wherein the second filtered signal is configured to be summed at the first filtered signal and the second filtered signal, a portion of the first filtered signal being cancelled based on the cancellation audio signal received at the feedback sensor.

In certain examples, one or more projection filters may be selected based on particular vehicle operating conditions, which may affect the acoustic relationship between the second location (e.g., microphone) and the third location (e.g., occupant's ear) and/or the transfer path between the first location (e.g., transducer) and the third location (e.g., occupant's ear), also referred to as a quadratic path transfer function. Thus, the particular vehicle and/or powertrain operating conditions upon which the filter selection is based may include one or more of the following: engine rotation Rate (RPM), transmission RPM, engine output torque (τ), transmission output torque, throttle position, manifold vacuum, engine spark timing/rate, rate of change of engine and/or transmission RPM (e.g., delta-RPM, Δ RPM), load/weight and distribution thereof, acceleration (transferring load to rear suspension), braking/deceleration (transferring load to front suspension), steering/cornering acceleration (transferring load from side to side), and/or suspension control and/or damper stiffness (e.g., hydraulic, pneumatic, electronically controlled suspension components).

In particular examples, one or more projection filters may be selected based on particular conditions that may affect the sound transmission effect of the cabin, which may affect the relationship between the second and third locations and/or the transfer path between the first and third locations. The conditions on which the filter selection is based may include one or more of: window position (degree of opening/closing), sunroof position (degree of opening/closing), door ajar (e.g., hatch open or closed), seat position (e.g., height, tilt, front/rear), rear seat fold down or stow, seat rate (number of occupants, which seats, weight, etc.), as may be detected by airbag occupant sensors, cameras, etc.

In various examples, the one or more projection filters include at least one prediction filter such that the estimate of the undesired sound at the third location is an estimate of the undesired sound at the third location at a future point in time.

Still other aspects, examples, and advantages of these exemplary aspects and examples are discussed in detail below. Examples disclosed herein may be combined with other examples in any manner consistent with at least one of the principles disclosed herein, and references to "an example," "some examples," "an alternative example," "various examples," "one example," etc. are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described may be included in at least one example. The appearances of such terms herein are not necessarily all referring to the same example.

Drawings

Various aspects of at least one example are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. The accompanying drawings are included to provide illustration and a further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the drawings, like or nearly like components illustrated in various figures may be represented by like reference characters or numerals. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

FIG. 1 is a schematic diagram of an exemplary sound cancellation system;

FIG. 2 is a schematic diagram of another exemplary sound cancellation system;

FIG. 3 is a schematic diagram of an exemplary tuning system;

FIG. 4 is a schematic diagram of another exemplary sound cancellation system;

FIG. 5 is a schematic diagram of another exemplary sound cancellation system;

FIG. 6 is a schematic diagram of another exemplary sound cancellation system; and is

Fig. 7 is a schematic diagram of another exemplary sound cancellation system.

Detailed Description

Sound cancellation systems that cancel or reduce undesired sound in a predetermined volume, such as harmonic cancellation in the vehicle cabin, typically employ a feedback sensor (such as a microphone) to generate an error signal (or feedback signal) indicative of residual, unremoved sound. The error signal is fed back to an adaptive filter that adjusts the cancellation signal in an attempt to minimize the residual uncancelled sound.

However, in some circumstances, the feedback sensor may not be positioned at an optimal location. For example, in a vehicle environment, the feedback sensor may be placed in the roof, pillar, or headrest, but should eliminate undesired sound at the passenger's ear. Thus, the error signal is indicative of an error at the feedback sensor and not at the ear of the passenger. This is undesirable because the purpose of the cancellation system is to cancel the undesired sound at the passenger's ear. However, placing the microphone on the passenger's ear is impractical and may be unacceptable to the passenger. However, in some examples, an a priori measurement by a microphone placed at the ear location may determine the acoustic relationship between the ear location and the feedback sensor location. Thus, the feedback sensor signal (e.g., the overhead microphone) may be "projected" to the equivalent ear microphone signal. In other words, the rooftop microphone signal may be filtered (based on the acoustic relationship between the two locations) to provide a virtual ear microphone signal. In various examples, the acoustic relationship between the feedback sensor position and the passenger ear position may vary according to vehicle and cabin conditions as described herein, such that the filter may be selected based on such vehicle and/or cabin conditions.

Further, in vehicles and other environments, sound cancellation audio signals are typically delayed by approximately five milliseconds because the audio signals must travel from speakers disposed along the perimeter of the vehicle cabin to the passenger's ear (e.g., the cancellation audio signal must travel from approximately five feet from the passenger's ear, and the speed of sound is approximately one foot per millisecond). This delay prevents optimal cancellation because the cancellation audio signal perceived by the passenger is directed to the sound that has occurred. Thus, some examples may include features that predict future values of residual sound at the occupant's ear without placing a microphone at the occupant's ear. FOR additional details regarding predicted or residual sounds, see U.S. patent No. 10,629,183 entitled "SYSTEMS AND METHODS FOR NOISE-candidate use detection", published on 21/4/2020, which is incorporated herein in its entirety FOR all purposes.

Various examples disclosed herein relate to a cancellation system that estimates an error signal representative of residual uncancelled sound at a location remote from a feedback sensor. In an example, the estimation is based on available information from i.e. remote reference microphones, and available information from knowledge of the relationship between these remote microphones and the sound field at the passenger's ear, and the output of the sound cancellation system itself.

The resulting adjustment of the adaptive filter based on the estimated error signal will minimize the estimated error signal, thereby eliminating undesired sound at the remote location rather than at the feedback sensor, e.g., effectively projecting the feedback sensor at the remote location. This may alternatively be understood as displacing the cancellation zone from the feedback sensor to a location remote from the feedback sensor.

Fig. 1 is a schematic diagram and/or signal flow diagram of an exemplarysound cancellation system 100 that includes asignal source 110, acancellation filter 120, a transducer 130 (e.g., a speaker or driver), a microphone 140 (feedback sensor), and anadaptation module 150. In various examples, signalsource 110 may be a signal generator that provides areference signal 112 that may contain components representing harmonics of a rotating device associated with the environment. For example, in a vehicle, a drivetrain, such as an engine, transmission, transaxle, wheels, etc., may generate various harmonics that produce audible sound in the vehicle. Thenoise cancellation system 100 may be configured to reduce audible harmonics. Accordingly, thesignal source 110 may generate areference signal 112 that represents a harmonic of the rotating device. Thus, in some examples, signalsource 110 may receive rotation information, such as a rate of rotation, which may be in Revolutions Per Minute (RPM), fromsensor 114. In some examples, thereference signal 112 may include a plurality of sinusoidal signals of various frequencies representing one or more harmonics of the rotating equipment.

Thecancellation filter 120 receives thereference signal 112 and filters thereference signal 112 to produce acancellation signal 122. Thecancellation signal 122 is a driver signal that drives thetransducer 130 to produce a cancellationaudio signal 132 in the environment (e.g., in the cabin of the vehicle, in some examples). Themicrophone 140 is a feedback sensor that detects sounds in the environment and provides anerror signal 142. Theadaptation module 150 receives thereference signal 112 and theerror signal 142 and updates thecancellation filter 120 to minimize theerror signal 142. Accordingly, theadaptation module 150 adjusts thecancellation filter 120 such that harmonic sounds at themicrophone 140 are reduced.

In the exemplarysound cancellation system 100 of fig. 1, if themicrophone 140 is ideally located at the occupant's ear, the system will effectively reduce or remove the sound of harmonics at the occupant's ear. Cancelling theaudio signal 132 via a transfer function 160 (T)_DE) To themicrophone 140, which is the transfer function from the driver (the location of the transducer 130) to the ear (the location of the microphone 140). In various examples,adaptation module 150 may be programmed with an estimate oftransfer function 160 and may implement an adaptive algorithm, such as any of various Least Mean Squares (LMS) or alternative algorithms, to adjust transfer function W ofcancellation filter 120 to adjust thesameThe error signal 142 is minimized.

While the examplesound cancellation system 100 of fig. 1 contemplates themicrophone 140 being located at or very near the ear of the occupant, it may often be unacceptable or impractical to place the microphone near the ear of the occupant. In various examples, rather, such feedback microphones may be located near but away from the occupant's ears, such as the roof, canopy, headrest, pillar, or elsewhere.

Fig. 2 shows another exemplarysound cancellation system 200 that is similar to thesound cancellation system 100, except that the feedback sensor (microphone 240) is located away from the occupant'sear 244. Thus, the error signal 242 from themicrophone 240 may not represent an undesired sound at the location of the occupant'sear 244. Thesound cancellation system 200 of fig. 2 operates in the same or similar manner as thesound cancellation system 100 of fig. 1, and thus may reduce the sound of harmonics at the location of themicrophone 240, but not necessarily at theear 244 of the occupant. Thus, thesound cancellation system 200 is not optimized to reduce harmonic sound at theears 244 of the occupant.

However, there is arelationship 246 between the sound at the location of themicrophone 240 and the sound at the location of theear 244 of the occupant. Therelationship 246 depends on the source and the manner in which audible vibrations are transmitted from the source and through the sound transmission effects of the environment. For example, when operating at a particular frequency, the particular harmonic may form a particular relationship 246 (e.g., in amplitude and phase) between the sound of the harmonic at the occupant'sear 244 and the sound of the harmonic at themicrophone 240. In various examples, different harmonics may formdifferent relationships 246 even when operating at the same frequency (e.g., a first harmonic may form a particular frequency at a given RPM, while a second harmonic forms a particular frequency at a lower RPM) (e.g., a 100Hz sound signal may be the first harmonic at one RPM and the second harmonic at another RPM). Further, in various examples, therelationship 246 may vary with any of a variety of operating conditions (such as torque, acceleration, vehicle load, etc.) as well as the acoustic characteristics of the environment (such as seat position, window condition, vehicle occupancy, load, age, etc.).

In various examples, therelationship 246 is measured a priori for any number of harmonics of interest (to accommodate different system objectives) and under various conditions, and a projection filter is generated to filter theerror signal 242 to effectively account for or reverse the effect of therelationship 246, such that the filtered signal represents an estimate of the error signal at theear 244 of the occupant. According to various examples,relationship 246 is measured for each harmonic across a range of rotation rates, and thus across a range of corresponding frequencies.Relationship 246 can then be equivalently modeled as a transfer function as a function of frequency, e.g., a set of phase and amplitude relationships across a range of frequencies for a given harmonic. Thus, in various examples, the projection filter transfer function effectively projects themicrophone 240 to the location of the occupant'sear 244, and may be referred to herein as W_REAs it relates the remote location (e.g., the roof location in some examples) to the ear location.

Fig. 3 illustrates anexemplary tuning system 300 that may be used in some examples to measure one ormore relationships 246 between sound at an ear location and sound at a remote location under various conditions. Themicrophone 140 is positioned at an ear location and themicrophone 240 is positioned at a remote location, e.g., where in operation it will be located, e.g., on a roof, ceiling, pillar, etc. Based on the rate of rotation (e.g., RPM) of the device for which it is desired to change/cancel sound, thesinusoidal source 310 provides selected harmonics 320(k) (e.g., k ═ 1, 2, 3, …, n), such as according to the expression in (1):

where k is the harmonic number and the rotation Rate (RPM) is expressed in revolutions per minute. The mixer 330 mixes the sinusoidal signals with the respective signals from themicrophones 140, 240 to provide an ear phasor (E)_k) And remote phasors (R)_k)。

For the sake of clarity, it is preferred that,each phasor includes amplitude and phase information. Although the phase of the audio source (rotating device) may be ambiguous, the phasor E is expected_kAnd phasor R_kHave substantially constant relative phases, e.g., the phase of one is fixed relative to the phase of the other, and likewise have their relative amplitudes, and such characterizes therelationship 246 for a given harmonic k at a given RPM. A plurality of such measurements are made at each of a plurality of rotation rates. The frequency of harmonic k varies with rotation rate, and thusrelationship 246 can be characterized as a set of amplitude and phase relationships across a range of frequencies for a given harmonic k.

Thus, therelationship 246 can be equivalently viewed as a transfer function between two locations, e.g., an ear location (e.g., microphone 140) and a remote location (e.g., microphone 240), the transfer function being a phase and magnitude relationship across a range of frequencies, such as from "input" to "output". Thus, a filter with an associated transfer function may take into account the remote location of themicrophone 240, e.g., such that the filter "projects" the microphone's signal to the ear location, e.g., as if themicrophone 240 were located at the ear.

In some examples, such a transfer function may be considered an actual transfer function of acoustic energy to a first location of the locations and as it progresses to a second location. This may be applicable to audio from a given source and under certain operating conditions. For example, a first harmonic of 100Hz (k ═ 1) from the engine may form aparticular relationship 246, but a second harmonic of 100Hz (k ═ 2) may form a different relationship. Also, a 100Hz tone from a speaker in a vehicle will likely form a very different relationship because the source location of the tone and its transmission to both locations will be distinct from the first engine harmonic of 100 Hz.

In various examples, multiple measurements may be taken at each rotation rate for each harmonic k, and an average phase and amplitude relationship may be used for a given harmonic and rotation rate. Additionally, and as presented in more detail below, therelationship 246 for a given harmonic and rotation rate may depend on additional parameters, such as torque, load, window position, and the like. In various examples, multiple measurements may be taken at different torques (or other changes in operating parameters), and the average phase and amplitude relationships may be used for a given harmonic and rotation rate under "average" torque operating conditions.

For example, in some examples, multiple measurements may be taken under a range of positive torque conditions, and the average of these measurements is used when the vehicle is operating at positive torque. Also, in some examples, multiple measurements may be made over a series of negative torque conditions, and the average of these measurements is used when the vehicle is operating at negative torque. Additionally, some examples may include multiple measurements made at multiple substantially neutral torque conditions, and using an average of these measurements when the vehicle is operating at substantially neutral torque.

As described above, FIG. 3 is anexemplary tuning system 300, which is a temporary configuration that takes measurements to characterize therelationship 246 of various harmonics at various rotation rates. Various examples of sound cancellation systems according to those described herein will not include amicrophone 140 located at the ear of the occupant. Various sound cancellation systems herein include one or more projection filters, each of which applies a transfer function to the remote microphone signal (e.g., from microphone 240) for the purpose of estimating the signal that an ear microphone (e.g., microphone 140) will produce, if it is present.

Some examples may include multipleremote microphones 240, such as for multiple locations in a vehicle. Furthermore, some examples of tuning systems similar to the tuning system of fig. 3 may include multipleremote microphones 240, and may also includemultiple ear microphones 140, such as for each side of an occupant's head and/or for multiple occupants. Thus, R_kAnd E_kEach may be a column vector whose number of elements is the number of remote microphones and the number of ear microphones, respectively. In such examples, the transfer function of the projection filter (the filter that receives the remote microphone signal and estimates the ear microphone signal) may be a matrix. In other examples, such a transfer function may be viewed as a plurality of projection filters, each projection filter to beThe remote microphone location projects to the ear microphone location.

Many of the quantities discussed herein are related to spin rate, and each harmonic has a specific frequency at a given spin rate. Thus, for a given harmonic, the various quantities described will depend on the rotation rate, and therefore on the frequency. For simplicity, comments on the frequencies and/or rotation rates, such as "x (f)" and/or "x (rpm)", are omitted from further discussion below. Further, the harmonic index k may also be excluded in various cases, but it will be understood by those skilled in the art that each relationship and/or projection filter transfer function is across a range of frequencies and is specific to a particular harmonic.

Wheremultiple relationships 246 have been measured for particular harmonics at various rotation rates, the projection filter as described herein operates by transferring a function W through the projection filter_REThe remote microphone signal (R) "projects" or is converted to an estimated ear microphone signal, as in the relationship in equation 2

Given E from a tuning system similar to that in FIG. 3_kAnd R_kCan design the projection filter transfer function W in various ways_RE. In at least one example, the projection filter transfer function W can be determined according to equation 3_RE：

Where "H" is the hermitian and the bars in number represent the expected value or average of multiple measurements. The above expression represents E based on the make estimate_kAnd reality E_kIn at least one example of error minimization therebetweenAt least one form of a transfer function of the filter. In various examples, other forms of projection filter transfer functions may be derived by minimizing other quantities or parameters.

According to various examples, the projection filter transfer function W is applied according to an exemplarysound cancellation system 400 as shown in FIG. 4_RE. Thesound cancellation system 400 includes aprojection filter 440 that receives the error signal 242 from themicrophone 240 and filters it to generate an estimatederror signal 442. The estimatederror signal 442 is thus an estimate of the error signal that has been provided by the ear microphone, e.g., with reference to fig. 1, which is an estimate of theerror signal 142 that has been provided by themicrophone 140, where themicrophone 140 is an ear microphone. As described above, various examples may includemultiple microphones 240 and may estimate multiple ear microphones, and thusprojection filter 440 may be a multiple-input and/or multiple-output filter, e.g., W_REMay be a matrix or a vector.

With continued reference to fig. 4, and as described above, thedriver 130 generates a cancellationaudio signal 132 that is also picked up by themicrophone 240. As described above, W is converted_RESpecific to a particular noise source (e.g., an engine) and specific harmonics from that noise source. Thus, for canceling theaudio signal 132, the projection filter transfer function W_REIs incorrect, e.g., it does not accurately estimate the cancelingaudio signal 132 at the ear position of the occupant. Thus, any component of the error signal 242 from the cancellationaudio signal 132 at themicrophone 240 is substantially a corrupted signal. Accordingly, various examples may include one or more additional filters to correct such components.

As described above, thecancellation signal 122 is the driver signal D that drives thetransducer 130 to produce the cancellationaudio signal 132. Therefore, the content in theerror signal 242 as a result of canceling theaudio signal 132 can be described by the expression in (4):

W_RE×T_DR×D (4)

where D is the driver signal (e.g., the cancellation signal 122) and T_DRFrom the driver signal to the remote microphone 240A transfer function of the location. In various examples, T_DRMay be a measured transfer function and/or an estimated value.

Fig. 5 illustrates another exemplarysound cancellation system 500 similar to thesound cancellation system 400, which includes additional filters to compensate for "corruption" in the estimatederror signal 442 caused by the cancellationaudio signal 132 processed by theprojection filter 440. In short, thesound cancellation system 500 subtracts the "impairment" component as described above in (4) from theestimation error signal 442 to produce a signal representing an estimate of the undesired signal at the occupant's ear, without being affected by the cancellationaudio signal 132. Thesound cancellation system 500 also adds the effect of the cancellationaudio signal 132 at the occupant's ear to produce a signal that is an estimate of the residual undesired signal at the occupant's ear, which is an estimated error signal that theadaptation module 150 can use to update thecancellation filter 120.

Referring specifically to fig. 5, thesound cancellation system 500 includes afirst correction filter 510 that receives thedriver signal 122 and outputs an estimated value of the "corrupted" portion of the estimated error signal 442 (see, e.g., (4) above), which is then subtracted from the estimatederror signal 442 by acombiner 520. Thesound cancellation system 500 further comprises asecond correction filter 530 that receives thedriver signal 122 and outputs an estimate of the actual contribution of the cancellationaudio signal 132 at the occupant's ear, which is then added by acombiner 540 to produce a correctedestimation error signal 542. In various examples, thesecond correction filter 530 applies a transfer function T_DEAs described above, this transfer function is a quadratic path transfer function from the driver to the position of the ear of the occupant (or an estimated value thereof).

Fig. 6 illustrates an exemplarysound cancellation system 600 that is a simplification of thesound cancellation system 500 of fig. 5. Thesound cancellation system 600 combines thefirst correction filter 510 and thesecond correction filter 530 with asingle correction filter 610 that receives thedriver signal 122 and outputs a combinedcorrection signal 612, and adds it to the estimatederror signal 442 via acombiner 620 to produce a corrected estimatederror signal 542.

In various examples, the transfer function ofcorrection filter 610 may be insignificant, such as when the "impairment" component as described in (4) above is substantially equivalent to the actual contribution of the cancellationaudio signal 132 at the passenger's ear. In such cases, thecorrection filter 610 may be omitted and the system may be simplified back to a system substantially as shown in fig. 4.

As noted above, any of thevarious relationships 246 for a particular harmonic may vary based on any one or more of: engine rotation Rate (RPM), transmission RPM, engine output torque (τ), transmission output torque, throttle position, manifold vacuum, engine spark timing/rate, rate of change of engine and/or transmission RPM (e.g., delta-RPM, Δ RPM), load/weight and distribution thereof, acceleration (transferring load to rear suspension), braking/deceleration (transferring load to front suspension), steering/cornering acceleration (transferring load from side to side), and/or suspension control and/or damper stiffness (e.g., hydraulic, pneumatic, electronically controlled suspension components).

Thus, in various examples, different transfer functions W for the projection filter may be selected based on changes in any of the above-described operating parameters of the vehicle_REAnd/or different transfer functions W for correction filters_DE. For simplicity, in the following description, examples are presented with respect to selecting different transfer functions based on torque τ, but it should be understood that any of the above-described operating parameters or other operating parameters may serve as a basis for selecting, changing, retrieving, or storing a transfer function for any of the projection filter and/or the correction filter.

Fig. 7 illustrates another examplesound cancellation system 700 that adjusts the transfer function of one or more of theprojection filter 740 and/orcorrection filter 710 based on an indication of torque τ (e.g., from the torque sensor 730) to produce an (corrected) estimatederror signal 742.

In various examples, the filter transfer function for a particular torque may be passedDetermined by taking measurements (e.g., via the tuning system 300) over a number of runs recorded at the particular torque, and/or the projected filter transfer function W for the particular torque_RECan be estimated by evaluating the expected value recorded at that particular torque. In various examples, by measuring or determining each of positive and negative torques, a reduced number of filter transfer functions W may be used_RE、W_DE(e.g., to reduce storage requirements). For example, the mechanism for transmitting harmonic sounds into the vehicle cabin may differ significantly when the driveline is at positive and negative output torques. In various examples, multiple levels of positive torque, negative torque, and in some cases neutral torque (e.g., coasting) may each have a determined projection. Thus, various examples may store multiple filter transfer functions W_RE、W_DEEach of which may be selected and applied based on current vehicle operating conditions (such as torque), but in various examples, any number of additional operating conditions are included, as variously described above. In some examples, a system or method may be interpolated between those transfer functions for which the record and filter transfer functions are determined for operating conditions. For example, in at least one example, the system may have stored filter transfer functions W associated with torque values of-50 Newton meters (Nm), 0Nm, and 200Nm_RE、W_DEAnd the filter transfer function may be interpolated between, for example, stored transfer functions of 0Nm and 200Nm, when the current torque is 100 Nm.

In addition to vehicle powertrain operation and loading as described above, therelationship 246 for the various harmonics and the transfer function 160 (secondary path) from thetransducer 130 to the occupant'sear 244 may vary as the environmental (e.g., cabin) sound transmission effects change. Accordingly, various examples of sound cancellation systems or algorithms herein may dynamically change (adjust, select) the projection filter transfer function and/or correct the filter transfer function based on changes in the cabin sound transmission effects.

In various examples, changes in car sound transmission effects may be communicated via digital control signals and may include, for example, window open/closed conditions (which window and degree), sunroof open/closed conditions (and degree), hatch door open/closed conditions, rear seat conditions (fold down, stow, etc.), cargo/load and occupancy, such as how many occupants are in the car, on which seats and how large they are, among others. For example, the occupancy may be estimated by data from airbag occupant sensors in the seat. In some examples, the camera, video, and/or facial recognition system may also provide information about the condition of the cabin.

Although examples have been described herein with respect to eliminating or reducing harmonics of a rotating device, the example systems, methods, and program code may be advantageously applied to enhancement or other modification of harmonic sound signals. In such examples, the cancellation filter as described herein may be an enhancement filter configured and adapted to provide an enhancement signal that causes the transducer to provide an enhanced audio signal to modify the sound of one or more harmonics at the ear of the occupant. The feedback sensor (remote microphone) may be "projected" to the occupant's ear position in a manner similar to those exemplary systems and methods described above. Thus, in such examples, one or more of the projection filters and/or correction filters may be applied in a manner similar to the examples described herein to provide an estimated signal representative of the sound at the occupant's ear, and the enhancement filters (other cancellation filters) may be adjusted to achieve the target sound of one or more harmonics.

In various examples, harmonic enhancement, reduction, or elimination may be performed for multiple occupant positions. For example, aremote microphone 240 may be included to detect acoustic energy at more than one location, and multiple projection filters and correction filters may be stored for multiple occupant ear locations. In such examples, harmonic enhancement, reduction, or elimination may be performed for selected occupant positions according to actual occupancy rates and/or user selections. For example, rear seat occupants may be detected, and the exemplary systems herein may operate to reduce harmonics at the ears of the rear occupants, while also reducing harmonics at the ears of the operator (e.g., in the driver's seat). However, when no rear occupants are detected and/or harmonic reduction in the rear seat position is disabled based on user selection, the system may disable harmonic reduction at the ear position of the rear occupants. Disabling harmonic reduction at one or more locations may enable better harmonic reduction performance at other locations, as such systems may minimize harmonic sound content at fewer locations.

Although the examples herein have been described with respect to a vehicle environment, the example systems, methods, and program code may be advantageously applied to the cancellation, enhancement, or other modification of harmonic sound signals in other environments, such as industrial, manufacturing, factory, power production, or other environments that may involve rotating equipment that may generate undesirable harmonic noise.

The functions described herein, or portions thereof, and various modifications thereof (hereinafter "functions"), may be implemented at least in part via a computer program product, e.g., a computer program tangibly embodied in an information carrier, e.g., in one or more non-transitory machine-readable media or storage devices, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers, and/or programmable logic components.

A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers that are distributed at one site or across multiple sites and interconnected by a network.

The acts associated with implementing all or part of the functionality may be performed by one or more programmable processors executing one or more computer programs to perform the functions of the calibration process. All or part of the functionality can be implemented as, special purpose logic circuitry, e.g., an FPGA and/or an ASIC (application-specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Components of a computer include a processor for executing instructions and one or more memory devices for storing instructions and data.

While several inventive examples have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining one or more of the results and/or advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive examples described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive examples described herein. It is, therefore, to be understood that the foregoing examples are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive examples may be practiced otherwise than as specifically described and claimed. Inventive examples of the present disclosure are directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.

Claims (28)

1. A sound cancellation system comprising:

a transducer configured to receive a cancellation signal and to generate a cancellation audio signal in a vehicle;

a microphone configured to provide an error signal representative of acoustic energy at a first location in the vehicle; and

a projection filter configured to filter the error signal to provide an estimated error signal at a second location in the vehicle, the projection filter selected based on a condition of the vehicle; and

an adaptation module that adjusts the cancellation signal based on the estimation error signal.

2. The sound cancellation system of claim 1, wherein the condition of the vehicle is one of a powertrain operating condition or a cabin sound condition.

3. The sound cancellation system of claim 1, wherein the condition of the vehicle is one or more of a rate of rotation, a rate of change in rate of rotation, a torque, a load, a manifold vacuum, and an acceleration rate.

4. The sound cancellation system of claim 1, further comprising a correction filter configured to filter the cancellation signal to provide a correction signal, the correction signal being combined with the estimated error signal to provide a corrected estimated error signal, the sound cancellation system being configured to adjust the cancellation signal based on the corrected estimated error signal.

5. The sound cancellation system of claim 4, wherein the correction filter is selected based on the condition of the vehicle.

6. The sound cancellation system of claim 1, further comprising a cancellation filter that receives harmonic signals and provides the cancellation signal, the sound cancellation system configured to adjust the cancellation signal by adjusting the cancellation filter.

7. A sound cancellation system comprising:

a cancellation filter that receives a harmonic signal related to a rotating device and provides a cancellation signal;

a transducer coupled to the cancellation filter, the transducer receiving the cancellation signal and producing a cancellation audio signal in an environment;

a microphone configured to provide an error signal representative of acoustic energy at a first location in the environment;

a projection filter configured to filter the error signal to provide an estimated error signal at a second location in the environment; and

an adaptation module that adjusts the cancellation signal based on the estimation error signal.

8. The sound cancellation system of claim 7, wherein the projection filter is selected based on an operating condition of the rotating device or a sound condition of the environment.

9. The sound cancellation system of claim 8, wherein the operating condition is one or more of a rate of rotation, a rate of change in rate of rotation, a torque, a load, a manifold vacuum, and an acceleration rate.

10. The sound cancellation system of claim 7, further comprising a correction filter configured to filter the cancellation signal to provide a correction signal, the correction signal being combined with the estimated error signal to provide a corrected estimated error signal, the adaptation module being configured to adjust the cancellation signal based on the corrected estimated error signal.

11. The sound cancellation system of claim 10, wherein the correction filter is selected based on an operating condition of the rotating equipment or a sound condition of the environment.

12. A method of canceling sound, comprising:

converting the cancellation signal into a cancellation audio signal in a cabin of the vehicle;

detecting, by a feedback sensor, an error signal at a first location in the car, the error signal being representative of acoustic energy at the first location;

filtering the error signal via a projection filter to provide an estimated error signal at a second location in the vehicle cabin, the projection filter selected based on a condition of the vehicle; and

adjusting the cancellation signal based on the estimated error signal.

13. The method of claim 12, wherein the condition of the vehicle is one of a powertrain operating condition or a sound condition of the cabin.

14. The method of claim 12, wherein the condition of the vehicle is one or more of a rate of rotation, a rate of change in rate of rotation, a torque, a load, a manifold vacuum, and an acceleration rate.

15. The method of claim 12, further comprising: the cancellation signal is filtered via a correction filter to provide a correction signal, the correction signal is combined with the estimated error signal to provide a corrected estimated error signal, and the cancellation signal is adjusted based on the corrected estimated error signal.

16. The method of claim 15, wherein the correction filter is selected based on the condition of the vehicle.

17. The method of claim 12, further comprising filtering harmonic signals via a cancellation filter to provide the cancellation signal, and adjusting the cancellation signal by adjusting the cancellation filter.

18. A method of adjusting harmonic sounds, comprising:

filtering a harmonic signal related to the rotating equipment to provide a cancellation signal;

converting the cancellation signal to a cancellation audio signal in the environment;

receiving an error signal representative of acoustic energy at a first location in the environment;

filtering the error signal to provide an estimated error signal at a second location in the environment; and

adjusting the cancellation signal based on the estimated error signal.

19. The method of claim 18, wherein filtering the error signal to provide an estimated error signal is based on an operating condition of the rotating equipment or a sound condition of the environment.

20. The method of claim 19, wherein the operating condition is one or more of a rate of rotation, a rate of change in rate of rotation, a torque, a load, a manifold vacuum, and an acceleration rate.

21. The method of claim 18, further comprising filtering the cancellation signal to provide a correction signal, combining the correction signal with the estimated error signal to provide a corrected estimated error signal, adjusting the cancellation signal based on the corrected estimated error signal.

22. The method of claim 21, wherein filtering the cancellation signal to provide a correction signal is based on an operating condition of the rotating equipment or a sound condition of the environment.

23. A non-transitory computer-readable medium having instructions recorded thereon, which when executed by one or more processors, cause the one or more processors to perform a method, the method comprising:

providing a cancellation signal to be converted into a sound signal in the environment;

receiving an error signal from a feedback sensor at a first location in the environment, the error signal being representative of acoustic energy at the first location;

filtering the error signal by a projection filter to provide an estimated error signal at a second location in the environment, a transfer function of the projection filter being selected based on an operating condition of a rotating device; and

adjusting the cancellation signal based on the estimated error signal.

24. The computer readable medium of claim 23, wherein the operating condition is one of a vehicle powertrain operating condition or a vehicle cabin sound condition.

25. The computer readable medium of claim 23, wherein the operating condition is one or more of a rate of rotation, a rate of change in rate of rotation, a torque, a load, a manifold vacuum, and an acceleration rate.

26. The computer-readable medium of claim 23, further comprising filtering the cancellation signal via a correction filter to provide a correction signal, combining the correction signal with the estimated error signal to provide a corrected estimated error signal, and adjusting the cancellation signal based on the corrected estimated error signal.

27. The computer-readable medium of claim 26, wherein the correction filter is selected based on the operating condition.

28. The computer readable medium of claim 23, further comprising filtering harmonic signals related to the rotating equipment to provide the cancellation signal.

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